1. Field of the Invention
The present invention generally relates to a protective device for a compressor. More particularly, it relates to a compressor protective device for a refrigerator that senses an abnormal state of a refrigerator compressor such as an overvoltage or an overload during operation; and delays the turned-off operation of the compressor for a predetermined period of time to prevent the compressor from being turned on or turned off frequently at the near threshold value, thereby more stably operating the compressor.
2. Description of the Related Art
A compressor is a device that compresses a refrigerant in a gaseous state by rotation of a rotor or reciprocation of a piston, and is essentially employed for a refrigerator or an air conditioner. An overload or overvoltage that occurs in the compressor increasing the pressure of the refrigerant may cause damage to the compressor and decrease the life expectancy of the compressor. Thus a proper measure against an overload or overvoltage is required.
Japanese Patent Unexamined Publication No. hei 4-218801 is a related art, and concerns a power cutoff circuit for an air conditioner. This air conditioner, which applies a signal line power to a driving part turning on or turning off transistors of an inverting part when an AC (alternating current) voltage output from the inverting part is applied to a compressor motor, includes: a -reset part that produces a reset signal for resetting a micom (microcomputer) for a given period of time upon application of the power, and generates an inverted output of the reset signal; and a transistor circuit that is capable of stopping the application of the signal line power and releasing the cutoff by the inverted output of the reset signal, and carries out the cutoff of the signal line power at the time of resetting the microcomputer.
The above-mentioned Japanese Patent does not propose a specific method of protecting the compressor, and cuts-off the signal line power during reset by resetting the microcomputer after application of power in order to simply prevent damage to the components at the time of the application of power. This patent does not disclose a method of controlling the turn-on/turn-off operation of the compressor by sensing an abnormal state such as an overvoltage or overload during operation.
In the meantime, the compressor of the above related art employs a mechanical overload protective device for cutting off the overload or overvoltage. This mechanical overload protective device senses that the electric power is increased as the pressure of a water pipe within the compressor is lowered when the overload or overvoltage occurs to thereby detect the overload, and cuts off the voltage, which takes time and causes damage to the compressor.